The present invention relates to a new and improved method of, and apparatus for, controlling the operating conditions prevailing at a ring spinning machine, by means of a control or monitoring apparatus which travels from spinning position to spinning position, there being consecutively checked at each spinning position the presence of a yarn or thread which is being formed thereat and for the absence of fiber lap-ups on at least one of both delivery rolls of the drafting arrangements.
A ring spinning machine for the final spinning process of a yarn or thread--hereinafter conveniently usually referred to as simply a yarn--consists of a large number of spinning positions, as a rule exceeding 400 spinning positions. Each spinning position is provided with a drafting arrangement where the infed fiber material, also referred to commonly in the art as roving, is drafted to the final yarn fineness or count and subsequently is spun into a yarn. Twist is imparted to the spun yarn and the same is wound by means of a spindle and ring arrangement.
Notwithstanding continuous efforts it has heretofore not been possible to avoid the occurrence of end or yarn breakages at a spinning position between the drafting arrangement and the spindle. This relatively rare event, however, is extremely troublesome since it involves both production losses and additional expenditure in work. Furthermore, there is brought about losses of material inasmuch as the loose fibers, which continue to emerge from the pair of delivery rolls of the drafting arrangement, are on longer caught by the twist of the formed yarn but infed by means of a suction nozzle of a yarn suction device to a collector or collecting device.
It happens now and again that such loose fibers, instead of moving into the suction nozzle, lap-up on one or both delivery rolls. This fiber lap-up increases in size as long as the supply of fibers is not interrupted, or as long as the yarn forming process is not reestablished. Failure to interrupt such undesirable lap-up formation ultimately will result in damage to the drafting arrangement of the involved spinning position or location. Therefore, in the spinning plant the operating personnel must continuously control and monitor the operating conditions of the ring spinning machine. The broken yarn ends must be pieced-up, and any possible fiber lap-ups formed on the rolls must be previously eliminated.
In more recent times there have become known to the art equipment which attempts to replace the work of the operating personnel at the ring spinning machine by automation through the use of operating or servicing or control devices which perform two tasks:
(a) Scanning the operating conditions at the spinning position, i.e., detecting the formation of yarn, the presence of a fiber lap-up on the rolls of the drafting arrangement, or entry of the roving at the drafting arrangement and so forth.
(b) Performing an actual operating or servicing operation at the spinning location or position, such as, for instance, re-piecing the broken yarn, stopping the supply of material to the drafting arrangement and so forth.
These operations are performed as a function of the detected operating or working conditions at the relevant spinning position or location.
In the first instance the present invention is concerned with the detection or recognition of certain working or operating conditions at the spinning position. Various solutions, intended to perform this objective, have already been proposed in the art.
Thus, for instance in Swiss Patent No. 571,588 and the cognate U.S. Pat. No. 3,950,925 and German Patent Publication No. 2,339,654, there is disclosed a proposal for automatically piecing-up yarns on ring spinning machines by using a scanning device which simultaneously detects both the absence of the yarn and any lap-up on the delivery rolls. With this equipment a light source is directed at the path of travel of the strand of fibers emerging from the delivery rolls and which are not spun into a yarn. The fiber strand reflects the light beam onto a photocell. With this proposal there is exploited the fact that the path of travel of the spun-in strand of fibers, i.e. the yarn which is being formed, does not coincide with the path of travel of the strand which is not spun-in and which is sucked into the suction device of the ring spinning machine.
The detecting device is mounted upon a travelling control device. This equipment is associated with the drawback that there is needed an extremely precise guiding of the control device along the ring spinning machine, since the spacing between the prior mentioned respective paths of travel of the strands of fibers is extremely small. Such requisite precise guide devices are associated with high equipment expenditure, without which the control device cannot satisfactorily perform.
According to a second proposal the strand of fibers emerging from the delivery rolls is sucked-off and there is activated a sensor in the suction duct. However, the use of this equipment is limited to a non-travelling control device coordinated to individual spinning positions, and, thus, cannot be employed for control devices which migrate from spinning position to spinning position.
Moreover, from Swiss Patent No. 578,058 and the corresponding U.S. Pat. No. 4,030,281 there is known to the art a control device for an automatic yarn piecing device for ring spinning machines, which, among other features, contains mechanism for detecting the fiber lap-ups on the delivery rolls of the drafting arrangement. This mechanism comprises two rolls provided with axial openings. These rolls are mounted at the immediate vicinity of the delivery rolls. Now, if a fiber lap-up develops on a delivery roll, then the roll is set into rotation owing to contact of the lap-up with the roll, and such is detected for each roll by means of a light beam and a photocell. Instead of using an optical control system there is also proposed a contact tongue for the lower, metallic delivery roll.
Mechanical scanning of the delivery roll is associated with the drawback that there is here also required an extremely precise and expensive guiding of the control device along the machine. This structure equally is of relatively complicated design, thereby detrimentally influencing its price and operational reliability.